Mercruiser inline 6 cyl. 165 exhaust riser...Looking for info

Hello, I have a 22ft Grady White with an inline 6 cylinder 165 mercruiser motor. The exhaust manifold on the motor was cracked from over heating, I do have some water mixed in with the oil, could it be from the water getting in from the cracked manifold? Also, I am buying new parts for the motor from Barr marine parts and there are two different options for an exhaust riser. One they have is the direct replacement part, exactly the same as the one that came out but Barr offers a new style riser that has a stainless steel extra part built into the riser that helps mix the water going through it with the exhaust fumes to help something, the guy on the phone from Barr said that he has no idea why they did it and he thought it wasnt even worth it. They cost about the same price but im not sure which way to go. Has anyone ever heard of this and if so what did you do, or if anyone has any knowledge on this or has even ever heard of it i would appreciate it if you would talk with me to help me figure this out. Im 20 years old working on my first boat trying to get it running good.
Thanks, Dakota

Re: Mercruiser inline 6 cyl. 165 exhaust riser...Looking for info

22Gradywhite said:

Hello, I have a 22ft Grady White with an inline 6 cylinder 165 mercruiser motor. The exhaust manifold on the motor was cracked from over heating, I do have some water mixed in with the oil, could it be from the water getting in from the cracked manifold? Also, I am buying new parts for the motor from Barr marine parts and there are two different options for an exhaust riser. One they have is the direct replacement part, exactly the same as the one that came out but Barr offers a new style riser that has a stainless steel extra part built into the riser that helps mix the water going through it with the exhaust fumes to help something, the guy on the phone from Barr said that he has no idea why they did it and he thought it wasnt even worth it. They cost about the same price but im not sure which way to go. Has anyone ever heard of this and if so what did you do, or if anyone has any knowledge on this or has even ever heard of it i would appreciate it if you would talk with me to help me figure this out. Im 20 years old working on my first boat trying to get it running good.
Thanks, Dakota

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Ayuh,.... Welcome Aboard,....
I'd sooner think the manifold, 'n the block Froze fulla water, 'n cracked 'em both...
Not sayin' it can't happen with an overheat, just not so likely...

I'd do abunch more diagnostic testin' before I spend money on parts....

Donno 'bout the risers,... probably a saltwater feature....

Re: Mercruiser inline 6 cyl. 165 exhaust riser...Looking for info

Manifolds crack for 2 reasons... 1 - freezing full of water... 2 - These particular manifolds have a history of cracking if the boat was run bow up and then bought to a quick stop. The cold water runs into the front of the manifold which was devoid of water and chills the very hot metal too quickly.. The first problem requires a thorough check of the engine block for cracking in it, and then a new manifold. The second problem just needs a new manifold, with the water reversing system installed (see service bulletin 86-13)..

Your other question about 'riser'... Are you using the right terminology? A riser is a spacer, usually either 3" or 6", that goes between the manifold and the exhaust elbow. You will find them on engines in larger boats where the exhaust elbow is not high enough above the water line to stop water flowing back into the manifold. We don't see many of them. Elbows on the other hand, are a 'U' shaped casting that takes the exhaust gas and the water leaving the cooling system and mixes them together before that mixture is sent down the exhaust pipe to the outside world.

Chris......

Re: Mercruiser inline 6 cyl. 165 exhaust riser...Looking for info

Your other question about 'riser'... Are you using the right terminology? A riser is a spacer, usually either 3" or 6", that goes between the manifold and the exhaust elbow. You will find them on engines in larger boats where the exhaust elbow is not high enough above the water line to stop water flowing back into the manifold. We don't see many of them. Elbows on the other hand, are a 'U' shaped casting that takes the exhaust gas and the water leaving the cooling system and mixes them together before that mixture is sent down the exhaust pipe to the outside world.

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Ayuh,.... Yer Right Chris,.... but American slang, those are the Risers....

We refer to Elbow bein' the cast piece, between the riser, 'n the y-pipe...
'course,.. on the In-lines, the riser dumps right into the down-pipe...

Hasn't this come up before, 'tween Us..??